This invention relates to an interchangeable storage medium on which a data file and a program, which subjects the data file to processing so that the file can be utilized by a computer system, are stored in correlated form, to a method of writing/reading data files to/from an interchangeable storage medium, and to a computer system in which this interchangeable storage medium is used as a data input/output medium.
In order to make it possible for a data file that has been stored on an interchangeable storage medium such as a floppy disk or optical disk to be utilized by a computer system, the prior art is such that software for utilizing the data that have been stored on the interchangeable storage medium is required to be stored in the computer system beforehand.
Consequently, a user who desires to use data that have been stored on an interchangeable storage medium is required to register the software (program) for utilizing the data in the computer system, before the data are utilized, in conformity with the format of the data stored on the interchangeable storage medium and the method of keeping the data in storage. The result is poor operability. Moreover, if the software cannot be registered, the data that have been stored on the interchangeable storage medium cannot be utilized. In particular, there are cases where data stored on an interchangeable storage medium can be utilized in one computer system or operating system (OS) but not in another computer system or operating system. In such case it is not possible to perform an exchange of data between computer systems having different architectures or between different operating systems.
Further, in a case where it is desired to limit the computer systems (operating systems) or users that are capable of utilizing data stored on an interchangeable storage medium, or in a case where it is desired to allow data read only and inhibit data write, such control cannot be performed in simple fashion.
Furthermore, according to the prior art, the reading of a data file is performed upon specifying the file name. This means that a data file cannot be read in simple fashion using a retrieval keyword and that a plurality of data files cannot be read using a single retrieval keyword.
Furthermore, a conventional operating system accesses a data file upon defining fixed units of data length (clusters) as well as the layout thereof. If the cluster length is short, therefore, a highly disjointed state is produced and write/read performance deteriorates in the case of data of great length, such as moving-picture data. Conversely, if cluster length is enlarged, unused areas are produced and space efficiency declines when data of comparatively small length, such as text data, are recorded.